Winter Surveys - Counting birds
For the winter survey we are looking for counts of birds, as well as a list of species for each block. Counting may seem straightforward, but can be challenging for anyone who has not done detailed bird surveys before.
For all of the winter surveys we are looking for counts of the total number of birds that you detect (see or hear). We do not want you to extrapolate and try to estimate how many there are in the total area, because different people are prone to do this in different ways. If the protocols are followed carefully, we have statistical methods that will help us to describe actual abundance patterns in a standardized manner.
One of the main challenges with counting birds is to be sure that you are not counting the same individuals more than once. Avoiding double-counting is tricky, but paying careful attention to where you saw or heard an individual, counting the birds in a group carefully (and repeating counts two or three times), and noting whether birds stay in place as you go by or move in a direction that means they might be seen again, can all reduce the risk of error.
Writing down what you see, as you go – rather than trying to remember everything until the end of the survey is also important. All of the data forms have space on them where you can tally individuals, either by marking them down one at a time or by writing subcounts, which can be totaled at the end of the survey. See example, below:
Notice that this observer used a mixture of methods, writing in numbers sometimes (especially for more abundant species) and tally marks in others (rock pigeon, snow goose). Exactly how you do this is up to you, as long as the totals are clearly identified in the “Count” column. If you use a mixture of methods, however, be careful in cases where tally marks might look like real numbers. For example, in this case the tally marks indicating 2 snow geese could be read as 11 snow geese. Adding up totals immediately after finishing the survey reduces the chance of errors.
A second problem is estimating the numbers of birds in flocks. In an ideal world, we would like you to count each individual. In reality, however, when birds are flying by, or shifting their position within a flock, doing this is hard, if not impossible. Simply looking at a flock and estimating the number is also known to be inaccurate, but there is evidence that people can get better at estimating abundance with practice.
One useful trick is to learn to count by groups. For example, count 10 individuals and get a sense of what that looks like. Then count how many times that sized group repeats through the flock. For larger flocks, count 20, or 50, or 100, and use the same process.
David Sibley has produced a nice summary of the issues associated with counting birds. Rather than repeating the same information, we hope that you will read what he has written on his web site. This site also includes a great quiz that you can use to train yourself to estimate group size.